Low ambient outdoor coil restrictor plate for air conditioner

ABSTRACT

A low ambient cooling system for a variable refrigerant flow heat pump includes an outdoor air conditioning unit and an indoor air conditioning unit. The outdoor air conditioning unit includes an outdoor heat exchanger with one or more valves that selectively control refrigerant flow through different sections of condenser coils during a low ambient cooling mode. During the low ambient cooling mode, the condenser coils of the outdoor heat exchanger include an active coil section through which refrigerant flows and an inactive coil section that is closed. An outdoor-coil restrictor plate with holes is attached to the active condenser coil in the outdoor air conditioning unit. The outdoor-coil restrictor plate restricts excessive heat release from the active coil section of the condenser coils in the outdoor heat exchanger during the low ambient cooling mode.

TECHNICAL FIELD

The subject matter described below relates generally to low ambient restrictor plate for an outdoor coil of an air-conditioning system. More particularly, the described subject matter relates to a low ambient restrictor plate that reduces the release of heat from condenser coils of an outdoor air conditioning unit during a cooling mode in low ambient conditions.

BACKGROUND

In general, an air-conditioning system based on a heat pump design transports heat to, and from, an indoor air-conditioned space. Heat is transferred between the indoor space and the outdoor environment via an outdoor heat exchanger and an indoor heat exchanger that are connected through piping that circulate a heat medium (e.g., a refrigerant or water).

During a heating mode, the indoor unit provides heat to the indoor space. To do so, the outdoor unit absorbs heat from the outdoor ambient environment, transfers the absorbed heat to the refrigerant (e.g., by evaporating the refrigerant), circulates the refrigerant to the indoor unit where the indoor unit releases the heat to the indoor space (e.g., by condensing the refrigerant).

A heat pump essentially performs the reverse operation during a cooling mode. That is, the indoor unit absorbs heat from the indoor space (e.g., by evaporating the refrigerant), and the heat pump circulates the refrigerant to the outdoor unit where the outdoor unit releases the heat to the outdoor ambient environment (e.g., by condensing the refrigerant).

In some heat pumps, the heating mode and the cooling mode are performed seasonally. That is, the heating mode is performed during cold ambient temperatures and the cooling mode is performed during warm ambient temperatures. Traditional problems that exist for heat pumps may include how effectively heat is released to, or absorbed from, the ambient when a heating mode is performed during cold ambient temperatures and a cooling mode is performed during warm ambient temperatures. These problems are typically addressed by increasing heat absorption from cold ambient air or increasing heat release to warm ambient air.

However, certain heat pumps may also perform the cooling mode during cold ambient temperatures. Unlike traditional operations, performing a cooling mode during cold ambient temperatures presents unique problems. For example, the outdoor unit releases heat to the outdoor environment during a cooling mode by condensing the refrigerant. During warmer temperatures, heat pumps must essentially work against hotter outdoor temperatures to condense the refrigerant since heat must forcibly be released to a warm ambient.

In contrast, when an outdoor unit performs a cooling mode during cold ambient temperatures, the hotter outdoor temperature working against the condensing of the refrigerant is no longer an issue. Instead, a new problem may arise in that the cooler ambient temperature draws an excess amount of heat from the refrigerant as the outdoor unit condenses the refrigerant. This cooling mode during low ambient conditions may cause an uncontrolled drop in temperature and pressure beyond the predetermined temperature and pressure. During an uncontrolled drop in refrigerant temperature and pressure, the evaporator of the indoor units may freeze since the refrigerant has been overly cooled. As will be understood by one skilled in the art, these problems of performing a cooling mode in a low ambient environment become more dramatic during colder temperatures below freezing (e.g., below about 23° F. or −5° C.).

With these problems, general attempts to improve the capacity of a heat pump may exasperate the problems that arise during low ambient cooling. For example, approaches that increase heat release from the outdoor unit exasperate problems that occur during a cooling mode in cooler ambient temperatures, since it may cause excessive released from the condenser coil.

Attempts to address low ambient conditions may be focused on controlling the wind entering the outdoor unit. However, these approaches do not address the problems associated with uncontrolled release of heat from the outdoor coil itself. As discussed above, a major problem that occurs during a cooling mode in low ambient temperatures is uncontrolled release of heat from the coils of the outdoor heat exchanger. This uncontrolled release of heat may still occur even if wind is prevented from entering the outdoor unit due to the low ambient temperatures.

It would therefore be desirable to provide a outdoor coil restrictor plate that controls the release of heat from outdoor coils that are active during a cooling mode in low ambient conditions.

SUMMARY

A low ambient cooling system is provided for a variable refrigerant flow heat pump, that includes the following: an outdoor air conditioning unit that includes a compressor, a fan, and a housing that includes an air inlet and an air outlet; an outdoor heat exchanger that is installed in the housing of the outdoor air conditioning unit and that includes one or more valves configured to selectively control refrigerant flow through different sections of condenser coils during a low ambient cooling mode, the condenser coils of the outdoor heat exchanger include an active coil section through which refrigerant flows during the low ambient cooling mode and inactive coil section that is closed during the low ambient cooling mode; and an active-outdoor-coil restrictor plate that includes an inner surface attached to the active coil section, an outer surface opposite to the inner surface, an edge that connects the outer surface to the inner surface, and holes that extend from the outer surface to the inner surface to reduce excessive heat release from the active coil section of the condenser coils in the outdoor heat exchanger during the low ambient cooling mode.

The low ambient cooling system may further include an indoor air conditioning unit. The indoor unit includes an evaporator in the low ambient cooling mode and that is connected to the outdoor air conditioning unit through piping and an expansion valve.

The low ambient cooling system may further include a wind guard attached to the housing of the outdoor air conditioning unit.

The low ambient cooling block system may further include a controller configured to control the valves of the of the outdoor heat exchanger to selectively control refrigerant flow through the active coil section and the inactive coil section of the outdoor heat exchanger during the low ambient cooling mode.

The controller may be configured to control the valves to open refrigerant flow through the active coil section of the outdoor heat exchanger and to open refrigerant flow through the inactive coil section of the outdoor heat exchanger during a high ambient cooling mode.

The active-outdoor-coil restrictor plate may be reversibly fastenable to the active coil section of the outdoor heat exchanger.

The holes of the active-outdoor-coil restrictor plate are circular or rectangular. The active-outdoor-coil restrictor plate includes one or more rows of the holes, one or more columns of the holes, or both rows and columns of holes. The holes of the active-outdoor-coil restrictor plate may be uncovered. The holes in the active-outdoor-coil restrictor plate may be cutouts.

A method of restricting heat release in an outdoor heat exchanger during low ambient cooling is provided, which includes the following: providing an outdoor unit configured to perform a low ambient cooling mode, the outdoor unit includes condenser coils having an active coil section and an inactive coil section in the low ambient cooling mode; attaching an inner surface of an active-outdoor-coil restrictor plate to the active coil section of the condenser coils of the outdoor unit, the active-outdoor-coil restrictor plate includes holes; and restricting, via the active-outdoor-coil restrictor plate, heat release in the active coil section of the outdoor unit during the low ambient coiling mode.

The method may also include detecting an outdoor ambient temperature; determining whether the outdoor ambient temperature is at, or below, a predetermined temperature; and controlling the outdoor unit to perform the low ambient cooling mode in response to determining that the predetermined temperature is at, or below, the predetermined temperature.

The holes of the active-outdoor-coil restrictor plate in the method may be uncovered.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures where like reference numerals refer to identical or functionally similar elements and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate an exemplary embodiment and to explain various principles and advantages in accordance with the present disclosure.

FIG. 1 is a schematic diagram of a variable refrigerant flow air conditioning system according to disclosed embodiments.

FIG. 2 is a schematic diagram of the variable refrigerant flow air conditioning system of FIG. 1 during a cooling mode according to disclosed embodiments.

FIG. 3 is a schematic diagram of the variable refrigerant flow air conditioning system of FIG. 1 during a low ambient cooling mode according to disclosed embodiments.

FIG. 4 is a diagram of the outdoor coil restrictor plate attached to the active outdoor condenser coils of the outdoor heat exchanger in the low ambient cooling mode of FIG. 3 according to disclosed embodiments.

FIG. 5 is a diagram of the outdoor coil restrictor plate attached to the active outdoor condenser coils of the outdoor heat exchanger in the low ambient cooling mode of FIG. 3 according to disclosed embodiments.

FIG. 6 is a schematic diagram of the outdoor coil restrictor plate attached to the active coil section of the outdoor heat exchanger in the low ambient cooling mode of FIG. 3 according to disclosed embodiments.

FIG. 7 is a schematic diagram of the outdoor coil restrictor plate attached to the active coil section of the outdoor heat exchanger in the low ambient cooling mode of FIG. 3 according to disclosed embodiments.

FIG. 8 is a schematic diagram of the outdoor coil restrictor plate attached to the active coil section of the outdoor heat exchanger in the low ambient cooling mode of FIG. 3 according to disclosed embodiments.

FIG. 9 is a schematic diagram of the outdoor coil restrictor plate attached to the active coil section of the outdoor heat exchanger in the low ambient cooling mode of FIG. 3 according to disclosed embodiments.

FIGS. 10A and 10B are cross-sectional diagrams respectively showing the outdoor coil restrictor plate controlling the release of heat to the ambient before and after heat exchange occurs, respectively, according to disclosed embodiments.

FIG. 11 is a cross-sectional diagram showing the outdoor coil restrictor plate attached to the active coil section of the outdoor heat exchanger in an outdoor unit according to disclosed embodiments.

FIG. 12 is a cross-sectional diagram showing the outdoor coil restrictor plate attached to the active coil section of the outdoor heat exchanger in an outdoor unit that includes wind guards according to disclosed embodiments.

FIG. 13 is a cross-sectional diagram showing the outdoor coil restrictor plate attached to the active coil section of the outdoor heat exchanger in an outdoor unit that includes wind guards according to disclosed embodiments.

FIG. 14 is a flow chart showing a method of restricting heat release during the low ambient cooling of FIG. 3 with the outdoor coil restrictor plate according to disclosed embodiments.

DETAILED DESCRIPTION

The instant disclosure is provided to further explain in an enabling fashion the best modes of performing one or more embodiments. The disclosure is further offered to enhance an understanding and appreciation for the inventive principles and advantages thereof, rather than to limit in any manner the embodiments.

It is further understood that the use of relational terms, such as first and second, if any, are used to distinguish one from another entity, item, or action without necessarily requiring or implying any actual such relationship or order between such entities, items or actions. Some embodiments may include a plurality of processes or steps, which can be performed in any order unless expressly and necessarily limited to a particular order (i.e., processes or steps that are not so limited may be performed in any order).

FIG. 1 is a schematic diagram of a variable refrigerant flow heat pump 1 using the restrictor plate 30 on the outdoor heat exchanger 6. A low ambient cooling system of the present disclosure includes one or more of the components of the variable refrigerant flow heat pump 1. As shown in FIG. 1, the variable refrigerant flow heat pump 1 includes an outdoor unit 100 and an indoor unit 200. The outdoor unit 100 and the indoor unit 200 are connected by piping 300, which circulates a heat medium (e.g., refrigerant or water).

The outdoor unit 100 includes a housing 102 having an inlet 104 and an outlet 106. Within the housing 102 of the outdoor unit 100, the outdoor unit 100 includes a compressor 2, a four-way valve 4 (e.g., a reversing valve), an outdoor heat exchanger 6 (e.g., an outdoor coil), an outdoor fan 8 (e.g., a blower fan), a controller 10, an outdoor temperature sensor 12, and an expansion valve 14 (e.g., a metering valve). The outdoor unit 100 also includes an inactive coil valve 16 and an active coil valve 18 that are respectively opened and closed during a low ambient cooling mode, which is discussed further below. The inactive coil valve 16 and the active coil valve 18 selectively controlled (by, e.g., the controller 10) to control the flow of refrigerant through the different sections of the outdoor heat exchanger 6.

The indoor unit 200 includes a housing 202 having an inlet 204 and an outlet 206. Within the housing 202 of the indoor unit 200, the indoor unit 200 includes an indoor heat exchanger 20 (e.g., an indoor coil) and an indoor fan 22 (e.g., a blower fan).

The controller 10 is operatively connected to the components within the outdoor unit 100 and the indoor unit 200. For example, FIG. 1 shows that the controller 10 is communicatively connected to the outdoor fan 8, the indoor fan 22, the expansion valve 14, the inactive coil valve 16, the active coil valve 18, and the outdoor temperature sensor 12. The controller 10 may in some embodiments also be communicatively connected to other components of the variable refrigerant flow heat pump 1, such as the four-way valve 4 (e.g., to switch the flow of refrigerant between the outdoor unit 100 and the indoor unit 200) and the compressor 2 (e.g., to vary the operation frequency of a compressor 2 in some embodiments).

The controller 10 may be connected to the components of the variable refrigerant flow heat pump 1 through wired connections, wireless connections, or both. For ease of reference and illustration, the connections of the controller 10 are only explicitly shown in FIG. 1.

FIGS. 2 and 3 are schematic diagrams showing the variable refrigerant flow heat pump 1 in a cooling mode and a low ambient cooling mode, respectively. The flow of refrigerant is shown in bold through the piping 300 in FIGS. 2 and 3. The refrigerant may be any type of heat medium appropriate for a heat pump (e.g., refrigerant, mixed types of refrigerant, or water), as will be understood by one skilled in the art. The heat medium will be referred to as a refrigerant for ease of reference.

As shown in the cooling mode in FIG. 2, the variable refrigerant flow heat pump 1 transfers heat from the indoor unit 200 for release by the outdoor unit 100. In particular, refrigerant flows through the indoor heat exchanger 20, which operates as an evaporator to evaporate the refrigerant and absorb heat from an indoor space. The refrigerant then flows through the four-way valve 4 to the compressor 2. The refrigerant then flows to the outdoor heat exchanger 6 of the outdoor unit 100. The outdoor heat exchanger 6 of the outdoor unit 100 operates as a condenser to condense the refrigerant and release the heat to the ambient environment. The refrigerant then exits the outdoor heat exchanger 6 passes through an expansion valve 14 as the refrigerant returns to the indoor unit 200.

In FIG. 2, the variable refrigerant flow heat pump 1 performs a cooling operation during warm ambient temperatures. This type of cooling operation is referred to as a high ambient cooling mode. Because of this, the controller 10 opens both the inactive coil valve 16 and the active coil valve 18 during the cooling operation. This allows refrigerant to flow through each section of the outdoor heat exchanger 6 and provide an increased condenser coil surface area for heat release to the warm ambient environment.

On the other hand, FIG. 3 shows a low ambient cooling mode. During a low ambient cooling mode, the variable refrigerant flow heat pump 1 transfers heat absorbed by the indoor unit 200 to the outdoor unit 100. During the low ambient cooling mode, the indoor heat exchanger 20 operates as an evaporator with evaporator coils to absorb heat from the indoor space and the outdoor heat exchanger 6 operates as a condenser with concerns coils to release heat to the outdoor ambient environment.

During low ambient temperatures, the outdoor heat exchanger 6 may release an excessive amount of heat while condensing the refrigerant. When an excess amount of heat is released from the outdoor heat exchanger 6, the refrigerant becomes overly cooled. Left uncontrolled, this may cause the refrigerant in the indoor heat exchanger 20 operating as an evaporator to freeze.

Unlike the cooling mode in FIG. 2, the low ambient cooling mode in FIG. 3 shows that the controller 10 closes the inactive coil valve 16 of the outdoor unit and opens the active coil valve 18 of the outdoor unit 100. This allows refrigerant to flow only through a section of the coils in the outdoor heat exchanger 6.

During the low ambient cooling mode, the surface area of the coils in the outdoor heat exchanger 6 is reduced, since the cooler ambient temperature will facilitate heat release from the condenser coils of the outdoor heat exchanger 6.

While the variable refrigerant flow heat pump 1 can control the flow of refrigerant through certain sections of the outdoor heat exchanger 6 through operation of the inactive coil valve 16 and the active coil valve 18, this control alone may be insufficient to prevent the outdoor heat exchanger 6 from releasing an excessive amount of heat to the ambient environment.

In order to restrict the release of heat from the remaining active coil sections of the outdoor heat exchanger 6 that remain open to refrigerant flow during a low ambient cooling mode, the variable refrigerant flow heat pump 1 includes a restrictor plate 30.

FIGS. 4 and 5 are diagrams showing the restrictor plate 30 on a section of the condenser coils in the outdoor heat exchanger 6 during the low ambient cooling mode of FIG. 3. FIGS. 4 and 5 show a detailed view of the outdoor heat exchanger 6 in the refrigerant circuit of FIG. 3.

During the low ambient cooling mode, the outdoor heat exchanger 6 includes a first inactive coil section 24, a second inactive coil section 26, and an active coil section 28. FIG. 4 shows that the inactive coil valve 16 is closed to cutoff refrigerant flow through the first inactive coil section 24 and the second inactive coil section 26. FIG. 5 shows that the inactive coil valve 16 and a second inactive coil valve 17 are closed to respectively cutoff refrigerant flow through the first inactive coil section 24 and the second inactive coil section 26. FIGS. 4 and 5 show that the active coil valve 18 is opened to permit refrigerant flow (depicted in bold) through the active coil section 28.

FIGS. 4 and 5 show that a restrictor plate 30 is attached to the active coil section 28 of the outdoor heat exchanger 6. Each section of the outdoor heat exchanger 6 includes a coil, which serves as a condenser coil during the cooling mode and the low ambient cooling mode when active (i.e., open to refrigerant flow).

In FIGS. 4 and 5, the active coil section 28 includes an active condenser coil 40. The restrictor plate 30 is attached to the active coil section 28 to cover the active condenser coil 40, which restricts heat release from the active condenser coil 40 during the low ambient heat mode. The restrictor plate 30 may be referred to as, e.g., an outdoor coil restrictor plate or an outdoor active coil restrictor plate.

As shown in FIGS. 4 and 5, the restrictor plate 30 includes holes 32. The holes 32 expose portions of the active condenser coil 40. Because of this, the restrictor plate 30 restricts the release of heat from the active condenser coil 40 of the active coil section 28 by providing exposed portions 42 and unexposed portions 44 of the active condenser coil 40. The unexposed portions 44 are covered by the restrictor plate 30, and may be referred to as covered portions of the active condenser coil 40. The unexposed portions 44 of the active condenser coil 40 are depicted with dotted lines in FIGS. 4 and 5, and the exposed portions 42 of the active condenser coil 40 are depicted with solid lines in FIGS. 4 and 5 (in bold to show refrigerant flow).

This configuration allows the restrictor plate 30 to restrict the heat release from the active condenser coil 40 by allowing heat release from the exposed portions 42 of the active condenser coil 40 and restricting heat release from the unexposed portions 44 of the active condenser coil 40.

FIGS. 4 and 5 also show that the first inactive coil section 24 includes a first inactive coil 50 and that the second inactive coil section 26 includes a second inactive coil 52. However, the restrictor plate 30 in FIGS. 4 and 5 only covers the active coil section 28. That is, the restrictor plate 30 in FIGS. 4 and 5 does not cover any one of the first inactive coil section 24, the first inactive coil 50, the second inactive coil section 26, or the second inactive coil 52. The first inactive coil 50 and the second inactive coil section 26 are uncovered (as shown by the solid lines in FIGS. 4 and 5).

In combination with the variable refrigerant flow heat pump 1 and the corresponding control of the first inactive coil section 24, the second inactive coil section 26, and the active coil section, these features of the restrictor plate 30 provide greater control of the release of heat during low ambient cooling.

For example, the variable refrigerant flow heat pump 1 may be limited to reducing the flow of refrigerant to one predetermined section, such as the active coil section 28. However, the restrictor plate 30 provides further restriction, and control, of the release of heat from the active condenser coil 40 beyond the limitations of the control of the variable refrigerant flow heat pump 1 alone, such as through valve control.

Consequently, the combination of the variable refrigerant flow heat pump 1 and the restrictor plate 30 on the active coil section 28 allows greater restriction of the amount of heat released from the outdoor heat exchanger 6 during the low ambient cooling mode of FIG. 3. As noted above, this may prevent the refrigerant flowing through the outdoor heat exchanger 6 from releasing excessive heat, uncontrollably dropping in temperature and pressure, and causing the indoor unit 200 to freeze.

As discussed above and shown in FIGS. 4 and 5, the restrictor plate 30 includes holes 32 that are located at positions on the restrictor plate 30 across from the active condenser coil 40 that expose exposed portions 42 and cover the unexposed portions 44 of the active condenser coil 40. The shape, number, and type of holes 32 is not limited. The holes 32 may be, or formed from, cutouts or punch-outs. The restrictor plate 30 may include one or more rows of holes 32, one or more columns of holes 32, or a combination of both. The arrangement of holes 32 may be referred to as a pattern of holes 32. The pattern of holes 32 may be uniform or non-uniform.

For example, FIGS. 6-9 show different numbers and shapes of holes 32. In FIGS. 6-9 the outdoor heat exchanger 6 is shown with schematic representations of each section of the outdoor heat exchanger 6 (i.e., without depicting the coils). Note that in FIGS. 6-9 the restrictor plate 30 covers the active coil section 28 of the outdoor heat exchanger 6.

FIG. 6 shows the holes 32 of the restrictor plate 30 are circular and provided in two rows and four columns. This same pattern of holes 32 is also shown in FIGS. 1-5. As noted above, the shape, number, and arrangement of the holes 32 is not limited.

For example, FIG. 7 shows that the holes 32 may be oval-shaped. FIG. 7 shows an example of one row and five columns of holes 32. FIG. 8 shows an example of the holes 32 that are square-shaped. FIG. 9 shows an example of the holes 32 that are rectangular-shaped. As noted above, the holes 32 may be punch-outs or cutouts, which may be square-shaped or rectangular-shaped as shown in FIGS. 8 and 9. The shape, number, and/or arrangement of the holes 32 may be determined based on, e.g., operating conditions and/or economic factors.

FIGS. 10A and 10B are provided to illustrate the heat restriction by the restrictor plate 30. FIGS. 10A and 10B show a cross-sectional view of the outdoor heat exchanger 6 with a restrictor plate 30. As shown, the restrictor plate 30 covers the active coil section 28 of the outdoor heat exchanger 6. As with FIGS. 1-9, the first inactive coil section 24 and the second inactive coil section 26 remain uncovered in FIGS. 10A and 10B.

FIG. 10A shows that, during the low ambient heating mode, available heat 60 will form in the active coil section 28. This is because the active coil section 28 of the outdoor heat exchanger 6 operates as a condenser to condense the refrigerant and release heat to the outdoor, ambient environment. The heat available to be released to the ambient environment (i.e., the available heat 60) is depicted as unshaded arrows. The available heat 60 in FIG. 10A has not yet been released to the environment (i.e., no heat transfer has occurred).

Note that in FIG. 10A the available heat 60 collects through the entire active coil section 28 of the outdoor heat exchanger 6 as condenses refrigerant in the low ambient cooling mode. As noted above, the low ambient temperatures may cause the outdoor heat exchanger 6 to release an excessive amount of the available heat 60. As discussed above, the uncontrolled release of an excessive amount of available heat 60 may cause the evaporator coils of the indoor heat exchanger 20 to freeze.

FIG. 10B shows the restriction on heat release of the available heat 60. In FIG. 10B, the ambient heat 62 is shown as shaded arrows. As noted above, the low ambient cooling mode occurs during low ambient conditions (e.g., below about 23° F. or −5° C.). Because of the low ambient temperatures, restrictor plate 30 restricts the amount of available heat 60 released to the ambient environment. That is, the restrictor plate 30 reduces the amount of heat exchange to prevent an uncontrolled drop in temperature and pressure in the refrigerant during low ambient conditions as the outdoor heat exchanger 6 operates as a condenser (i.e., in the low ambient cooling mode).

FIG. 10B shows that ambient heat exchange 64 between the available heat 60 in the active coil section 28 and the ambient heat 62 only occurs with some of the available heat 60. As shown in FIG. 10B, some of the available heat 60 remains in the active coil section 28, and this remaining heat from the available heat 60 is shown as restricted heat 66. As will be appreciated by one skilled in the art, the available heat 60 in the active coil section 28 would be released in excess without the restrictor plate 30.

FIG. 10B shows that ambient heat exchange 64 occurs at the location of the holes 32 in the restrictor plate 30. More specifically, the ambient heat exchange 64 occurs at the exposed portions 42 of the active condenser coil 40 in the active coil section 28 (as shown, e.g., in FIGS. 4 and 5). Since ambient heat exchange 64 does not occur at the unexposed portions 44 of the active condenser coil 40, some of the available heat 60 in the active coil section 28 becomes restricted as restricted heat 66. This allows the restrictor plate 30 to restrict the release of heat to the cooler ambient environment during the low ambient cooling mode.

Without the restrictor plate 30, the active condenser coil 40 would be entirely exposed to the ambient environment. During low ambient cooling, this provides problems since an excess amount of available heat 60 will be released to the ambient environment through ambient heat exchange 64.

Furthermore, even though the variable refrigerant flow heat pump 1 can control which section of the outdoor heat exchanger 6 is active, the variable refrigerant flow heat pump 1 may be limited by, e.g., the control of refrigerant flow through the coils through inactive coil valve 16 and the active coil valve 18. During a low ambient cooling mode, the control of the inactive coil valve 16 and the active coil valve 18 may be inadequate to prevent excessive release of available heat 60 during low ambient temperatures.

On the other hand, the restrictor plate 30 in combination with the variable refrigerant flow heat pump 1 allows a greater control of the release of available heat 60 from active condenser coil 40 of outdoor heat exchanger 6. The restrictor plate 30 provides these features without a costly redesign of the configuration of the outdoor heat exchanger 6, the controller 10, and/or the variable refrigerant flow heat pump 1 to accommodate low ambient cooling conditions.

The restrictor plate 30 also utilizes a relatively small amount of space in the outdoor unit 100, since the restrictor plate 30 is flat. This allows the restrictor plate 30 to be installed without modifying either the components of the outdoor heat exchanger 6 or increase the area of space that the outdoor unit 100 occupies. The area that the space the outdoor unit 100 occupies (e.g., the footprint) is significant in residential and commercial settings.

FIGS. 11-13 show a cross-sectional view of the outdoor unit 100. FIG. 11 shows that the outdoor unit 100 includes an inlet 104 where ambient heat 62 primarily enters the housing 102 of the outdoor unit 100. FIG. 11 also shows that the outdoor unit 100 includes an outdoor heat exchanger 6, which operates as a condenser during the low ambient cooling mode. The outdoor unit 100 includes an outdoor fan 8, which may be located below the outlet 106 of the outdoor unit 100, as shown in FIG. 11.

The outdoor heat exchanger 6 includes an active coil section 28 with a restrictor plate 30. As shown in FIGS. 10A-13, an inner surface of the restrictor plate 30 is attached to the active coil section 28. The outer surface of the restrictor plate 30 is opposite to the inner surface of the restrictor plate 30, and connected to the inner surface via an edge (e.g., an edge that defines the periphery of the restrictor plate 30, such as a peripheral edge). The outer surface of the restrictor plate 30 faces, e.g., the inlet 104 in some embodiments. The holes 32 extend between the outer surface and the inner surface of the restrictor plate 30. The restrictor plate 30 may be reversibly fastened to the active coil section 28 of the outdoor heat exchanger 6 through one or more fasteners (e.g., screws, rivets, nuts, and/or bolts).

The outdoor unit 100 may include one or more wind guards 70 to block wind from entering the housing 102 of the outdoor unit 100. The wind guards 70 may be used in combination with the restrictor plate 30, as shown in FIGS. 11-13. However, the restrictor plate 30 is different from the wind guards 70, as the restrictor plate 30 restricts the release of heat from the active coil section 28 and the wind guards 70 blocks wind.

FIG. 12 shows that the wind guards 70 may be installed on one, or both, of the inlet 104 and the outlet 106 of the housing 102 of the outdoor unit 100. The wind guards 70 may include one or more louvers 72. FIG. 13 shows a different configuration of the outdoor unit 100. The outdoor unit 100 in FIG. 11 also includes a wind guard 70 installed on the inlet 104 of the housing 102. Note that the restrictor plate 30 is attached to the active coil section 28 of the outdoor heat exchanger 6 in each of the outdoor units 100 in FIGS. 10-13. The type of outdoor unit 100 is not limited so long as the restrictor plate 30 may be provided.

In addition, the outdoor heat exchanger 6 is depicted with a first inactive coil section 24 and a second inactive coil section 26. However, the number of inactive coil sections of the outdoor heat exchanger 6 is not particularly limited. For example, the outdoor heat exchanger 6 may include only two coil sections, which may correspond to the first inactive coil section 24 and the active coil section 28. The active coil section 28 is smaller than the inactive coil (e.g., one or both of the first inactive coil section 24 and the second inactive coil section 26).

FIG. 14 shows a flowchart for a method 1400 of restricting heat release in an outdoor heat exchanger during low ambient cooling. The flowchart in FIG. 14 includes Step 1402 of providing an outdoor unit 100. The outdoor unit 100 used in the method 1400 is connectable to a variable refrigerant flow heat pump 1, as shown in the variable refrigerant flow heat pump 1 of FIG. 1. The outdoor unit 100 can be seen, e.g., in FIGS. 11-13, which are discussed above.

Step 1404 in the method 1400 is to attach a restrictor plate 30 to the active coil section 28 of the outdoor heat exchanger 6 in the outdoor unit 100. The restrictor plate 30 may be reversibly attached to the active coil section 28 via fasteners (e.g., screws, rivets, nuts, and/or bolts). The fasteners may extend through the outer surface of the restrictor plate 30. The restrictor plate 30 restricts the release of available heat 60 in the active coil section 28 during a low ambient cooling mode.

Step 1406 of the method 1400 in FIG. 14 is to detect the outdoor ambient temperature. The outdoor temperature sensor 12 detects the outdoor ambient temperature. The controller 10 may also determine the outdoor ambient temperature based on a signal provided by the outdoor temperature sensor 12.

In Step 1408, the controller 10 determines whether the outdoor temperature is equal to, or less than, a predetermined temperature (e.g., 23° F. or −5° C.). The determination in Step 1408 may be made when the variable refrigerant flow heat pump 1 performs a cooling operation or a low ambient cooling operation.

If the controller 10 determines that the outdoor temperature is greater than the predetermined temperature, the controller 10 controls the variable refrigerant flow heat pump 1 to perform a high ambient cooling mode. The high ambient cooling mode can be seen in FIG. 2. In the high ambient cooling mode, the controller 10 opens both the inactive coil valve 16 and active coil valve 18. This allows refrigerant to flow through the condenser coils of the first inactive coil section 24, the second inactive coil section 26, and the active coil section 28 of the outdoor heat exchanger 6 in the outdoor unit 100. The controller 10 may operate the four-way valve 4 to switch the flow of refrigerant between the outdoor unit 100 and the indoor unit 200 of the variable refrigerant flow heat pump 1.

Note that the terms active and inactive refer to the refrigerant flow during low ambient cooling mode. Thus, refrigerant flows through the first inactive coil section 24 and the second inactive coil section 26 when the inactive coil valve 16 is opened in, e.g., the high ambient cooling mode, as shown in FIG. 2.

During the high ambient cooling mode, which can be seen in FIG. 2, the refrigerant flows between the indoor unit 200 and each of the sections of the outdoor heat exchanger 6 in the outdoor unit 100. In the high ambient cooling mode, heat is absorbed from the indoor space through the indoor heat exchanger 20 operating as an evaporator. The absorbed heat is then released through each of the sections of the outdoor heat exchanger 6.

On the other hand, in Step 1408 in the method 1400 of FIG. 14, if the controller 10 determines that the outdoor temperature is equal to, or less than, the predetermined temperature, the controller 10 control the variable refrigerant flow heat pump 1 to perform a low ambient cooling mode. The low ambient cooling mode is performed in Step 1412 of the method 1400. The low ambient cooling mode can also be seen in FIG. 3.

In the low ambient cooling mode, the controller 10 closes the inactive coil valve 16 and opens the active coil valve 18. The controller 10 may operate the four-way valve 4 to switch the flow of refrigerant between the outdoor unit 100 and the indoor unit 200. In the low ambient cooling mode, the indoor unit 200 absorbs heat from the indoor space and release heat to the ambient environment through the active coil section 28 of the outdoor heat exchanger 6 in the outdoor unit 100.

In Step 1414 of the method 1400 in FIG. 14, the restrictor plate restricts heat release from the active coil section 28 of the outdoor heat exchanger 6. That is, during the low ambient cooling mode, the heat is released through the holes 32 of the restrictor plate 30 from the exposed portions 42 of the active condenser coils 40. This restricts the amount of available heat 60 that is released to the low temperature ambient environment, as discussed further above.

Although not shown explicitly in FIG. 14, the method 1400 may also include a return loop from Step 1414 to Step 1406 in some embodiments. This allows the method 1400 to switch between the high ambient cooling mode of Step 1410 and the low ambient cooling mode of Step 1412 in a control loop.

The components of the variable refrigerant flow heat pump 1 and system described above are example components. As will be understood by one skilled in the art, the variable refrigerant flow heat pump 1 may include one or more of each of the components. For example, the variable refrigerant flow heat pump 1 may include more than one indoor unit 200, more than one outdoor unit 100, more than one valve, and more than one sensor. There may be more than one of the components described above in the indoor unit 200 and the outdoor unit 100. For example, the outdoor unit 100 may include more than one compressor 2. The system may also include more than one controller 10.

The controller 10 discussed above may include one or more processors and memory. The controller 10 may be, or include, e.g., a microcontroller, a microcomputer, or a digital signal processor. The memory can include a static memory (e.g., ROM, PROM, EPROM, masked), dynamic memory (e.g., RAM, SRAM, DRAM), and/or a hybrid memory (e.g., NVRAM, EEPROM, Flash) that holds information used by the controller 10. This can include one or more programs for operating the components of the variable refrigerant flow heat pump 1, data used by the controller 10 (e.g., predetermined temperatures), and/or technical information used by the controller 10. In various embodiments, the memory of the controller 10 may include a flash drive, a solid-state drive, a magnetic or optical drive, or any suitable memory device.

This disclosure is intended to explain how to fashion and use various embodiments in accordance with, not limit. the true, intended, and fair scope and spirit thereof. The foregoing description is not intended to be exhaustive, or limited to, the precise form disclosed. Modifications or variations are possible in light of the above teachings. The embodiments above are chosen and described to provide illustration of the principles as practical applications, and to enable one of ordinary skill in the art to utilize the various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the disclosure as determined by the appended claims, as may be amended during the pendency of this application for patent, and all equivalents thereof, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled. 

What is claimed:
 1. A low ambient cooling system for a variable refrigerant flow heat pump, comprising: an outdoor air conditioning unit that includes a compressor, a fan, and a housing that includes an air inlet and an air outlet; an outdoor heat exchanger that is installed in the housing of the outdoor air conditioning unit and that includes one or more valves configured to selectively control refrigerant flow through different sections of condenser coils during a low ambient cooling mode, the condenser coils of the outdoor heat exchanger include an active coil section through which refrigerant flows during the low ambient cooling mode and inactive coil section that is closed during the low ambient cooling mode; and an active-outdoor-coil restrictor plate that includes an inner surface attached to the active coil section, an outer surface opposite to the inner surface, an edge that connects the outer surface to the inner surface, and holes that extend from the outer surface to the inner surface to reduce excessive heat release from the active coil section of the condenser coils in the outdoor heat exchanger during the low ambient cooling mode.
 2. The low ambient cooling system according to claim 1, further comprising an indoor air conditioning unit that includes an evaporator in the low ambient cooling mode and that is connected to the outdoor air conditioning unit through piping and an expansion valve.
 3. The low ambient cooling system according to claim 1, further comprising a wind guard attached to the housing of the outdoor air conditioning unit.
 4. The low ambient cooling system according to claim 1, further comprising a controller configured to control the valves of the of the outdoor heat exchanger to selectively control refrigerant flow through the active coil section and the inactive coil section of the outdoor heat exchanger during the low ambient cooling mode.
 5. The low ambient cooling system according to claim 4, wherein the controller is configured to control the valves to open refrigerant flow through the active coil section of the outdoor heat exchanger and to open refrigerant flow through the inactive coil section of the outdoor heat exchanger during a high ambient cooling mode.
 6. The low ambient cooling system according to claim 1, wherein the active-outdoor-coil restrictor plate is reversibly fastenable to the active coil section of the outdoor heat exchanger.
 7. The low ambient cooling system according to claim 1, wherein the holes of the active-outdoor-coil restrictor plate are circular or rectangular.
 8. The low ambient cooling system according to claim 1, wherein the active-outdoor-coil restrictor plate includes one or more rows of the holes.
 9. The low ambient cooling system according to claim 8, wherein the active-outdoor-coil restrictor plate includes one or more columns of the holes.
 10. The low ambient cooling system according to claim 1, wherein the active-outdoor-coil restrictor plate includes one or more columns of the holes.
 11. The low ambient cooling system according to claim 1, wherein the holes of the active-outdoor-coil restrictor plate are uncovered.
 12. The low ambient cooling system according to claim 1, wherein the holes in the active-outdoor-coil restrictor plate are cutouts.
 13. A method of restricting heat release in an outdoor heat exchanger during low ambient cooling, comprising: providing an outdoor unit configured to perform a low ambient cooling mode, the outdoor unit includes condenser coils having an active coil section and an inactive coil section in the low ambient cooling mode; attaching an inner surface of an active-outdoor-coil restrictor plate to the active coil section of the condenser coils of the outdoor unit, the active-outdoor-coil restrictor plate includes holes; and restricting, via the active-outdoor-coil restrictor plate, heat release in the active coil section of the outdoor unit during the low ambient coiling mode.
 14. The method according to claim 13, further comprising detecting an outdoor ambient temperature, determining whether the outdoor ambient temperature is at, or below, a predetermined temperature; and controlling the outdoor unit to perform the low ambient cooling mode in response to determining that the predetermined temperature is at, or below, the predetermined temperature.
 15. The method according to claim 13, wherein the holes of the active-outdoor-coil restrictor plate are uncovered. 